This invention relates generally to flat panel display devices and particularly to a line cathode support structure for such devices.
U.S. Pat. No. 4,217,519 discloses a modulator structure for a flat panel display device. An insulative modulator support has a plurality of modulation electrodes disposed on one side. The support structure is affixed to an insulative baseplate which also supports a plurality of modulation electrodes. The modulation electrodes are electrically connected in pairs whereby one electrode for each pair is supported by the modulator support and the other by the baseplate. A line cathode is arranged across the entire transverse, or horizontal, dimension of the display device between the modulation electrode pairs. The display device is divided into channels and each includes a beam guide assembly having two spaced guide meshes between which electrons propagate as beams. The entrance to each of the beam guide assemblies is arranged between the modulation electrode pairs so that electrons from the cathode are injected into the spaces between the guide meshes.
U.S. patent application Ser. No. 125,822, filed Feb. 29, 1980 by M. A. Leedom now U.S. Pat. No. 4,330,735 and entitled "Beam Guide Structure For A Flat Panel Display Device" discloses a beam guide assembly which can be utilized along the modulator structure disclosed in the above referenced patent. The beam guide assembly includes two parallel spaced guide meshes between which electrons from a line cathode propagate as beams. Spaced from and parallel to the guide meshes is a focus mesh which cooperates with a plurality of extraction electrodes on the display device baseplate to focus the electron beams between the guide meshes. Arranged parallel to and spaced from the focus mesh is an acceleration mesh which accelerates the extracted electron beams toward the phosphor screen of the display device. The meshes of the beam guide assembly are held in the desired parallel relationship and spacing by a plurality of insulative support members which extend perpendicular to the surfaces of the meshes. One end of each support member extends a precise distance beneath the lower guide mesh to support the guide mesh assembly the precise distance above the extraction electrodes.
The devices disclosed in the referenced patent and patent application are multichannel devices which utilize a single line cathode to provide electrons to the guide mesh assemblies within every channel. It therefore is critical that the line cathode be aligned with the entrance to the guide mesh assemblies and that the position of the cathode with respect to such entrances be identical and permanent within very close tolerances. The instant invention solves these difficulties by the provision of a cathode support structure which precisely locates and supports a line cathode at the entrance to the beam guide assemblies of a flat panel display device.